Supporting linkage arrangement for earth working tool

ABSTRACT

A linkage arrangement for coupling a soil-working implement to a traction-vehicle by first and second intercommencted supporting members therebetween with the first and second members being relatively movable transversely of the linkage and controlled in said relative movement by constraining followers comprising upper and lower quadrants pivotably mounted for engagement of their arcuate surfaces against a respective bearing surface of a curved track defined by at least one of the first and second supporting members.

EEK [19] Gosling et al.

[ Mar. 11, 1975 SUPPORTING LINKAGE ARRANGEMENT FOR EARTH WORKING TOOL [76] Inventors: William Robert Frederick Gosling,

Olive House, Aldborough, Boroughbridge; David John Wakefield, 36 Pinewood Ave., Flanshaw Park; Terry Long, Leroyne, North Drive, Bramhope, all of England [22] Filed: June 4, 1973 [21] Appl. No: 366,962

[30] Foreign Application Priority Data June 2, 1972 Great Britain 25972/72 [52] 11.8. C1 172/239, 37/193, 172/677, 172/699, 403/61, 403/121 [51] Int. Cl. A01b 65/06, AOlb 13/08 [58] Field of Search 37/193; 61/726, 72.5,

[56] References Cited UNITED STATES PATENTS 3,032,903 5/1962 Ede 172/699 X 3,670,431 6/1972 Ede 37/193 Primary Examiner-Clifford D. Crowder Attorney, Agent, or Firm-Merriam, Marshall, Shapiro & Klose [57] ABSTRACT A linkage arrangement for coupling a soil-working implement to a traction-vehicle by first and second intercommencted supporting members therebetween with the first and second members being relatively movable transversely of the linkage and controlled in said relative movement by constraining followers comprising upper and lower quadrants pivotably mounted for engagement of their arcuate surfaces against a respective bearing surface of a curved track defined by at least one of the first and second supporting members.

13 Claims, 10 Drawing Figures PATENIED MARI 1 I975 sumanrgs PATENTEU MARI 1 I975 EMU 3 OF 6 PATENTEU MR] 1 I975 870, 1 O6 SHEET-6 95 g SUPPORTING LINKAGE ARRANGEMENT FOR EARTH WORKING TOOL The present invention relates to supporting linkages, and in particular to such linkages suitable for supporting and controlling rear-mounted, soil-working implements on traction vehicles. The invention is most particularly concerned with linkages which enable a mole to operate at an equilibrium depth when mounted on a traction vehicle such as a tractor, and which have a so-called floating action."

It is known that in producing a tunnel with a mole plough it is desirable to employ a tow bar or linkage having towing characteristics which permit automatic depth-correcting action, and so maintain an equilibrium working depth. Thus, it is required that, if the mole plough exceeds the equilibrium working depth, for example, it will be tilted upwards so as to be restored to that working depth. To effect the restoring action without excessive over-correction it is necessary that the towing characteristics should approximate to that of a rigid tow bar having a length of about four times the mean working depth (that is, for a working depth of 3 feet, a bar of 12 feet in length); and for this purpose there has been developed linkage systems, most notably quadrilateral linkage systems, which have advantages in manoeuvrability and weight saving over comparable rigid tow bars. Such a linkage is described in British Pat. No. 851,746, wherein there is provided a pair of interconnected supporting members, one adapted to be carried by a suitable vehicle and the other constituted by or attached to the upper end of the coulter blade of the mole plough, the two members being relatively movable in a generally vertical plane parallel to the axis of the mole; and constraining means for controlling the relative movement. The latter comprises a curved track in one supporting member and cooperating follower means, comprising rollers, constrained to engage and follow the track at at least two points spaced therealong, with the centre of curvature of the track lying ahead of the linkage so that the relative movement of the supporting members, and hence movement of the mole, is by rotation about the centre of curvature.

It is found in practice that the forces acting on the rollers of such a linkage system are extremely high and generally are of a level which, with normal roller bearing co-efficients of friction, make the frictional forces imposed by the tractor vary significantly. The main deleterious effect is to move the virtual hitch point (nominally at the centre ofcurvature of the guide link) to positions dependent on the direction of relative motion (or tendancy to motion between guide link and blade box). The resulting changes in pitching moment on the tractor can cause serious local track pressure problems due to the tendancy of the tractor to adapt a more down or more up position. In addition the pitching action of the tractor, correlated as it is in the grading action, makes the guide control system prone to instability.

In some circumstances rotation or sliding of the rollers. along the track is prevented altogether. Consequently, the linkage operates as a solid link and the machine will grade, in preference to rotation or sliding of the rollers, and vehicle pitch about the geometric pitch cannot be isolated from the blade.

The effects described above obviate the purpose and advantages of the linkage (i.e., connection of the blade to the tractor by means of a virtual rather than real hitch point) and remove its fine grade function.

As the reflected friction force is proportional to the ratio of the bearing radius to the outside radius of the guide rollers, it has been found that the problems of virtual hitch point movement and locking of the rollers can be overcome by using rollers of greater diameter, although it is found that diameters of the order of 50 to 60 inches are required and these clearly are impracticable. The present invention seeks to provide an improved linkage having the advantages of suitably enlarged rollers.

In one aspect of the present invention there is provided a linkage arrangement comprising first and second inter-connected supporting members each respectively adapted to be provided on first and second units to be coupled by said linkage, said first and second member being relatively movable transversely of the linkage and controlled in said relative movement by constraining follower means, wherein the follower means comprise an upper and lower quandrant pivotally mounted for engagement of their arcuate surfaces against a respective bearing surface of a curved track defined by at least one of the first and second supporting members.

By way of example, embodiments of the invention will be described hereinafter, from which features and advantages of the invention will appear, such description being given in conjunction with the accompanying drawings, in which:-

FIG. I shows a tractor-drawn mole plough having a linkage system according to a first embodiment;

FIGS. 2 to 4 show a side elevation, rear elevation and plan view, respectively, of the linkage system of FIG. 1;

FIGS. 5A and 5B show an exploded and assembled perspective view of the linkage system of FIG. 1;

FIG. 6 shows a view similar to that of FIG. 2 illustrating the manner of movement between the components of the linkage system; and

FIGS. 7 to 9 show views similar to those of FIGS. 2, 4 and 7 of a second embodiment of the invention.

With reference to FIGS. 1 to 5B, thereis shown a first unit in the form of a tractor 14 connected by linkage system 12, to a second unit in the form of a mole plough 10. The tractor 14 which provides the tractive effort necessary for drawing the plough during tunnel formation. The plough has a coulter blade 16, and a mole 18. On each side of the blade is a control fin 20, pivotable about pins 22 to provide stability and trim in varied ground conditions. Stability and trim also can be controlled by the action of hydraulic trim ram 24, the upper end of which is fixed relative to the blade 16, by pin 24a and which provides trim adjustment to the mole.

The other end of blade 16 is located within guide link 26 which comprises a first supporting member and forms the rear end of a parallel motion quadrilateral linkage 28. The guide link 26 is cage-like, having side openings 29 which define opposed curved bearing surfaces 32, 33 which are arcuate and coaxial, with their centre of curvature at a suitable distance infront of the mole. The blade 16 is secured within a second supporting member comprising floating blade box 30 by means of adjusting studs 34 and pin 35 and is engaged with guide link 26 by means of a pair of first quadrants 36 and a pair of second quadrants 38. The quadrants are pivotally mounted on pivot means in the form of stub shafts 40, which project from the blade box laterally of the plough, and are arranged with the arcuate surfaces of each pair in rolling engagement with a respective one of bearing surfaces 32, 33. The radius of each quadrant preferably is equal and is such that the effects of reflected friction loads is minimised so that the linkage is truly floating, even at tractive efforts of up to 120,000 lb/f.

Spigots 42 project laterally from the guide link 26 and prevent the quadrants from dropping from the shown positions when under zero or slight load conditions.

The linkages 28 includes, in addition to the guide link 26, a pair of equal and generally parallel rigid links 44, 46 secured at their forward ends to vertically spaced pivot points on the vehicle, and at the rearward ends to the guide link 26 by pins 44a and 46a. A ram 48 extends diagonally of the linkage 28 and can be hydraulically actuated to vary the length of the diagonal and so raise or lower the guide link 26 and provide grade actron.

The ram 48 holds the guide link 26 stationary relative to the tractor so that it follows any vertical movement of the tractor due to ground undulations. The mole 18 will then be controlled by the relative movements of the guide link 26 and the coulter blade 16, since the vertical movement of the former will result in a corresponding vertical movement of the centre of curvature of bearing surfaces 32, 33 through which the resultant force applied to the blade through quadrants 36, 38 continues to act. Thus with elevation of the guide link 26 the quadrants 36, 38 are caused to rotate in an anticlockwise direction in the arrangement as shown in FIG. 2, and the radial re-active forces directed towards shafts 40 are exerted on the quadrants by the bearing surfaces; these re-active forces applying a turning moment to the blade 16 which tends to elevate the leading end of the mole, causing it to rise to a new equilibrium level positioned above the former level a distance equal to the vertical movement of the guide link 26 and hence of the centre of curvature of the bearing surfaces. As the mole rises, there is a reversal of the relative movement between the blade 16 and the guide link 26, with clockwise rotation of the quadrants 36, 38. The relative movements are reversed in the event that the guide link is caused to drop. The quadrants are arranged so that at the equilibrium working depth they are at the centre of their permitted rotational movement and the geometric centre of curvature of the guide link control surfaces corresponds to the apparent hitch point of the mole plough, thereby permitting maximum vertical adjustment in either direction.

Removal of the mole from or introduction of it into the ground can be effected by extension or contraction, respectively, of ram 48 so as to move guide link 26 to an extreme upper or lower position relative to blade 16. The change in relative position of the guide link 26 and blade 16 for lowering the mole, compared with the relative position of operation at an equilibrium working depth as shown in FIG. 2, is shown in FIG. 6.

In order to counteract possible high side loads upon the blade due to steering action etc., the guide link 26 can be fitted (as shown in FIG. 6) with four guide rollers, one pair on top of the guide link (one of which is shown at 26a), and one pair (of which one roller is shown at 261)) on the bottom and fitted so that they are either side of the blade 16 stub where it projects from the top and bottom of the guide link 26 but not in contact in the equilibrium (i.e., no side loads) case. Small clearances between blade and rollers will facilitate this.

Additionally, thrust bearings 49 are positioned between the quadrants and the blade box to assist in maintaining the former in position. Conveniently the bearings 49 are located on studs 40, with journal bearings 490 preferably being positioned therebetween.

In the alternative arrangement shown in FIGS. 7 to 9, the coulter blade 16' is mounted rearwardly of the guide link 26, and secured by adjusting studs 34 and pin 35'. In this arrangement, the guide link comprises an open rectangular frame having inner bearing surfaces 32', 33; while the floating blade box 30, within which the blade 16' is secured, has a parallel pair of forwardly extending plates 50 between which the guide link 26' is located. Extending laterally of the blade from the inner surface of each plate 50 is a stub shaft on which are mounted an upper and lower quadrant 36, 38 each having its arcuate surface in rolling engagement with one of the bearing surfaces 32', 33' of the guide link 26. Side thrust bearings 52 are mounted on the snner face of each plate to facilitate relative movement between the plates and guide link 26'.

The operation of the second arrangement is analogous with that of the first arrangement.

We claim:

1. A linkage arrangement for inter-connecting first and second units, said arrangement comprising:

a. a first supporting member for connection to said first unit, the first supporting member defining first and second curved bearing surfaces;

b. a second supporting member for connection to said second unit and movable relative to said first supporting member, the second supporting member including first pivot means defining a first pivot axis nearer to said first bearing surface than to said second bearing surface and second pivot means defining a second pivot axis nearer to said second bearing surface than to said first bearing surface; and

c. follower means controlling relative movement of said first and second supporting members, the follower means comprising a first quadrant pivotally mounted adjacent the apex thereof by said first pivot means for movement about said first pivot axis with the arcuate surface thereof in contact with said second bearing surface and a second quadrant pivotally mounted adjacent the apex thereof by said second pivot means for movement about said second pivot axis with the arcuate surface thereof in contact with said first bearing surface.

2. A linkage arrangement according to claim 1 wherein the first and second bearing surfaces are opposed and have a common centre of curvature.

3. A linkage arrangement according to claim 1 wherein one of said supporting members comprises a cage-like member in which the other of said supporting members is movably received, said one supporting member being provided on opposed sides with openings the peripheries which each define a said curved bearing surface.

4. A linkage arrangement according to claim 3 wherein said first and second pivot means comprise journals extending substantially perpendicularly of said other supporting member.

5. A linkage arrangement according to claim 3 wherein said other supporting member provides means for attachment to a soil-working implement and said one supporting member provides means for attachment to a traction vehicle.

6. A linkage arrangement according to claim 5 wherein said one supporting member comprises an element of a quadrilateral linkage system by which it is attachable to a traction vehicle.

7. A linkage arrangement according to claim 3 wherein the first and second curved bearing surfaces have a common centre of curvature.

8. A linkage arrangement according to claim 1 wherein one of said supporting members comprises an open frame member, the opening of which defines said first and second curved bearing surfaces.

9. A linkage arrangement according to claim 8 wherein the respective bearing surfaces of said track have a common centre of curvature.

10. A linkage arrangement according to claim 8 wherein the other of said supporting members includes a pair of spaced, substantially parallel plate members between which the one supporting member is received, said first and second pivot means being journals extending between said plate members.

11. A linkage arrangement according to claim 10 wherein said other supporting member provides means for attachment to a soil-working implement and said one supporting member provides means for attachment to a traction vehicle.

12. A linkage arrangement according to claim ill wherein said one supporting member comprises one el ement of a quadrilateral linkage system by which it is attachable to a traction vehicle.

13. A linkage arrangement according to claim 10 wherein the respective bearing surfaces have a common centre Of curvature. 

1. A linkage arrangement for inter-connecting first and second units, said arrangement comprising: a. a first supporting member for connection to said first unit, the first supporting member defining first and second curved bearing surfaces; b. a second supporting member for connection to said second unit and movable relative to said first supporting member, the second supporting member including first pivot means defining a first pivot axis nearer to said first bearing surface than to said second bearing surface and second pivot means defining a second pivot axis nearer to said second bearing surface than to said first bearing surface; and c. follower means controlling relative movement of said first and second supporting members, the follower means comprising a first quadrant pivotally mounted adjacent the apex thereof by said first pivot means for movement about said first pivot axis with the arcuate surface thereof in contact with said second bearing surface and a second quadrant pivotally mounted adjacent the apex thereof by said second pivot means for movement about said second pivot axis with the arcuate surface thereof in contact with said first bearing surface.
 1. A linkage arrangement for inter-connecting first and second units, said arrangement comprising: a. a first supporting member for connection to said first unit, the first supporting member defining first and second curved bearing surfaces; b. a second supporting member for connection to said second unit and movable relative to said first supporting member, the second supporting member including first pivot means defining a first pivot axis nearer to said first bearing surface than to said second bearing surface and second pivot means defining a second pivot axis nearer to said second bearing surface than to said first bearing surface; and c. follower means controlling relative movement of said first and second supporting members, the follower means comprising a first quadrant pivotally mounted adjacent the apex thereof by said first pivot means for movement about said first pivot axis with the arcuate surface thereof in contact with said second bearing surface and a second quadrant pivotally mounted adjacent the apex thereof by said second pivot means for movement about said second pivot axis with the arcuate surface thereof in contact with said first bearing surface.
 2. A linkage arrangement according to claim 1 wherein the first and second bearing surfaces are opposed and have a common centre of curvature.
 3. A linkage arrangement according to claim 1 wherein one of said supporting members comprises a cage-like member in which the other of said supporting members is movably received, said one supporting member being provided on opposed sides with openings the peripheries which each define a said curved bearing surface.
 4. A linkage arrangement according to claim 3 wherein said first and second pivot means comprise journals extending substantially perpendicularly of said other supporting member.
 5. A linkage arrangement according to claim 3 wherein said other supporting member provides means for attachment to a soil-working implement and said one supporting member provides means for attachment to a traction vehicle.
 6. A linkage arrangement according to claim 5 wherein said one supporting member comprises an element of a quadrilateral linkage system by which it is attachable to a traction vehicle.
 7. A linkage arrangement according to claim 3 wherein the first and second curved bearing surfaces have a common centre of curvature.
 8. A linkage arrangement according to claim 1 wherein one of said supporting members comprises an open frame member, the opening of which defines said first and second curved bearing surfaces.
 9. A linkage arrangement according to claim 8 wherein the respective bearing surfaces of said track have a common centre of curvature.
 10. A linkage arrangement according to claim 8 wherein the other of said supporting members includes a pair of spaced, substantially paralLel plate members between which the one supporting member is received, said first and second pivot means being journals extending between said plate members.
 11. A linkage arrangement according to claim 10 wherein said other supporting member provides means for attachment to a soil-working implement and said one supporting member provides means for attachment to a traction vehicle.
 12. A linkage arrangement according to claim 11 wherein said one supporting member comprises one element of a quadrilateral linkage system by which it is attachable to a traction vehicle. 